Diabetes mellitus is a metabolic disease basically characterized by a chronic hyperglycemic state due to impaired insulin action. The treatment of diabetes is generally performed by drug therapy together with diet and exercise therapies. Oral hypoglycemic agents, which are one type of anti-diabetic agent, include biguanides and thiazolidinediones that improve insulin resistance; sulfonylureas and glinides that promote insulin secretion from pancreatic β cells; and α-glucosidase inhibitors that inhibit sugar absorption.
However, it is reported that they have side effects: biguanides produce gastrointestinal symptoms and lactic acidosis; thiazolidinediones produce weight gain and edema; sulfonylureas and glinides produce hypoglycemia or secondary failure due to long-term use; and α-glucosidase inhibitors produce diarrhea etc. Therefore, development of an oral hypoglycemic agent which can address such problems is desired. In recent years, compounds having new structures have been developed as oral hypoglycemic agents (see, for example, Patent Literature 1 to 9).